It's definitely a feature when you're starting out. But as the codebase grows and ages, it becomes a bug.

The problem is that the behavior becomes so complex and so much is pushed to runtime that there's no way to know what the code is actually doing. There's paths that are only going to be executed once a year, but you don't know which ones those are. Eventually, editing the code becomes very risky.

At this particular codebase, it was not uncommon to see 3, 4 or 5 functions that do more or less the same thing. Why? Because nobody dared change the behavior of a function, even if it's buggy. Maybe those bugs are the only thing keeping other bugs from cropping up. It's like wack-a-mole. You fix something, and then the downstream effects are completely unpredictable.

It becomes a self-eating snake. Because the codebase is so poor, it ends up growing faster and faster as developers become more risk-averse.